re PR tree-optimization/28807 (wrong code with may_alias and structs)

2006-08-24  Andrew Pinski  <pinskia@physics.uc.edu>

        PR tree-opt/28807
        * tree-ssa-operands.c (access_can_touch_variable): Don't say
        the access through a base which has an alias set of 0 cannot
        touch the variable.

2006-08-24  Andrew Pinski  <pinskia@physics.uc.edu>

        PR tree-opt/28807
        * gcc.c-torture/execute/mayalias-2.c: New test.
        * gcc.dg/tree-ssa/alias-13.c: New test.

From-SVN: r116393

gcc/ChangeLog

-2006-08-24  Bill Wendling <wendling@apple.com>
+2006-08-24  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	PR tree-opt/28807
+	* tree-ssa-operands.c (access_can_touch_variable): Don't say
+	the access through a base which has an alias set of 0 cannot
+	touch the variable.
+
+2006-08-24  Bill Wendling  <wendling@apple.com>
 
 	* doc/tm.texi (TARGET_DEFAULT_PACK_STRUCT): Fixed English.
 	

gcc/testsuite/ChangeLog

+2006-08-24  Andrew Pinski  <pinskia@physics.uc.edu>
+
+	PR tree-opt/28807
+	* gcc.c-torture/execute/mayalias-2.c: New test.
+	* gcc.dg/tree-ssa/alias-13.c: New test.
+
 2006-08-24  Jan Hubicka  <jh@suse.cz>
 
 	PR debug/26881

gcc/testsuite/gcc.c-torture/execute/mayalias-2.c

+struct S { short x; };
+typedef struct S __attribute__((__may_alias__)) test;
+
+int f() {
+  int a=10;
+  test *p=(test *)&a;
+  p->x = 1;
+  return a;
+}
+
+int main() {
+  if (f() == 10)
+    __builtin_abort();
+  return 0;
+}
+
+

gcc/testsuite/gcc.dg/tree-ssa/alias-13.c

+/* { dg-do link } */
+/* { dg-options "-O2" } */
+
+
+struct a
+{
+  char a1;
+};
+
+int *aa;
+
+void g(int *a)
+{
+  aa = a;
+  *a = 2;
+}
+
+int t(int i, struct a *b)
+{
+  g(&i);
+  b->a1 = 1;
+  i = 2;
+  if (b->a1 != 1)
+    link_failure ();
+}
+int main(void)
+{
+  struct a b;
+  t(1, &b);
+  return 0;
+}
+
+

gcc/tree-ssa-operands.c

@@ -1150,7 +1150,10 @@ access_can_touch_variable (tree ref, tree alias, HOST_WIDE_INT offset,
 	       || TREE_CODE (TREE_TYPE (base)) != UNION_TYPE)
 	   && !AGGREGATE_TYPE_P (TREE_TYPE (alias))
 	   && TREE_CODE (TREE_TYPE (alias)) != COMPLEX_TYPE
-	   && !POINTER_TYPE_P (TREE_TYPE (alias)))
+	   && !POINTER_TYPE_P (TREE_TYPE (alias))
+	   /* When the struct has may_alias attached to it, we need not to
+	      return true.  */
+	   && get_alias_set (base))
     {
 #ifdef ACCESS_DEBUGGING
       fprintf (stderr, "Access to ");